Two trains crashed head-on in southern Germany early Tuesday, leaving at least four people dead and 40 seriously injured, the German news agency DPA said.<br />More than three hours after the crash, emergency services were still trying to reach people trapped in the wreckage.<br />Police spokesman Stefan Sonntag told The Associated Press the two regional trains crashed near Bad Aibling, in Bavaria before 7 A.M. and that several wagons overturned.<br />"This is the biggest accident we have had in years in this region and we have many emergency doctors, ambulances and helicopters on the scene," Sonntag said.<br />A spokesman for German federal police in Bavaria, Matthias Knott, said that the region was very inaccessible and making rescue efforts more difficult.<br />The crash took place near the river Mangfall in a densely wooded and hilly region.